The term “Broadcasting in a continuous stream” denotes a mode of transmission of a multimedia content wherein a client equipment item can play the multimedia content as it receives it. “Broadcasting in a continuous stream” is better known by the term “streaming” or “live” broadcasting.
Streaming differs from “file downloading”. In file downloading, the client equipment item must first receive all the packets making up the multimedia content before it can start to play this multimedia content. There is no predetermined order or a predetermined time interval in which a fragment of the file must be received by its recipient.
In streaming, on the contrary, the stream fragments must be received in a predetermined time interval around the instant of receiving of a previous fragment of this same stream. If the fragment has not been received in the predetermined time interval, it is eliminated and will not be read by the multimedia reader. To do this, typically, each fragment is associated with a lifetime. If the fragment has not reached its recipient before its lifetime has elapsed, the fragment is destroyed. Thus, the playing of a television channel can start before all the fragments that make it up have been received. To do this, all the fragments generally take the same route in the Internet. For example, a previously established routing table is constructed and used for this purpose.
“Terminal-to-terminal” networks are better known by the term “Peer-to-peer” network.
Such a peer-to-peer network is formed by a large number of computers, known as peers, interconnected by an information transmission network. Typically, the information transmission network is the world-wide web, better known by the term “Internet”.
In a peer-to-peer network, a peer can download a fragment or chunk of a television channel from the buffer memory of any other peer of the peer-to-peer network that receives the same television channel. In this description, the peer that downloads the chunk is known as the “child peer” and the peer from which the child peer downloads the chunk is known as the “parent peer”. In a peer-to-peer network, each peer is able to play, generally at the same time, the roles of child peer and parent peer. Thus, a peer is capable of playing, at the same time, the roles of client, server and router to direct the chunks stored in its buffer memory toward the buffer memory of the child peers.
In a peer-to-peer network, a child peer contains a list of neighboring peers. This list contains identifiers of peers, called “neighboring peers”, of the peer-to-peer network that this peer knows and can therefore contact to try to download a chunk of the television channel. Typically, the identifier of a peer is its IP (Internet Protocol) address and a port number used to exchange information by way of the Internet with the computer application that manages the connection and the implementation of the peer-to-peer network. This application is called “peer-to-peer software program” here.
Streaming of television channels over peer-to-peer networks is developing quickly and it is supposed that there exists today a large number of viewers for each television channel thus broadcast. To date, to measure the audience of a television channel streamed over a peer-to-peer network, it has been necessary to equip a large number of peers with a recording device. This therefore entails the active participation of the viewer so that the latter accepts and installs this recorder on the computer that he connects to the peer-to-peer network (see for example patent application WO 2011 084 779).
Audience measurements constructed in this way are hardly exhaustive because of the necessarily limited number of peers equipped with the recorder.
The prior art is also known from:                Shahzad Ali, Anket Mathur and Hui Zhang: “Measurement of commercial peer-to-peer live video streaming”, School of Computer Science Carnegie Mellon University, Jan. 2, 2006,        US 2004/215698A1.        